/*
  将下面异步代码使用 Promise 的方法改进
  尽量用看上去像同步代码的方式
  setTimeout(function () {
    var a = 'hello'
    setTimeout(function () {
      var b = 'lagou'
      setTimeout(function () {
        var c = 'I ♥ U'
        console.log(a + b +c)
      }, 10)
    }, 10)
  }, 10)
*/
function task21(){
  const p1 = new Promise((resolve,reject)=>{
    setTimeout(()=>{
      let a = 'hello'
      resolve(a)
    },10)
  })
  const p2 = p1.then((a)=>{
    return new Promise((resolve,reject)=>{
      setTimeout(()=>{
        let ab = a + 'lagou'
        resolve(ab)
      },10)
    })
  })
  p2.then((ab)=>{
    setTimeout(() => {
      let c = 'I ♥ U'
      console.log(ab+ c)
    }, 10);
  })
}
task21()

